How to add a value in an empty field in Mysql?

Question

I’m spinning a query who needs to pick up the 5 first lines with limit 5. However, there are times when they will return less than 5 lines. The value comes empty, nor NULL, nor 0.

I try to make a case when, but keeps returning empty. Does anyone know how I can solve this?

My query this below:

select case when defail5  then 0 else defail5 end 
  from (select failure, count(failure) as defail5 
          from reparo.falhas_consolidadas 
         where  brand2 in ('LBG_DKT') 
           and week = 'week-5-16' 
         group by failure 
         order by count(failure) desc limit 4 offset 3) as tb1;